Implement FocusOnSelectedSource for WgcCapturerWin.

Previously, windows captured by WgcCapturerWin may have been occluded
by other windows with no functionality to bring them to the top of the
z order. This change implements FocusOnSelectedSource for
WgcCapturerWin to afford consumers this functionality, and match the
experience offered by current capturers.

Bug: webrtc:12664
Change-Id: I8bc067ade90fba0be66a9be57d3429ba54ba1ae0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215241
Reviewed-by: Jamie Walch <jamiewalch@chromium.org>
Commit-Queue: Austin Orion <auorion@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#33809}

modules/desktop_capture/BUILD.gn

@@ -147,7 +147,10 @@ if (rtc_include_tests) {
       if (rtc_enable_win_wgc) {
         sources += [ "win/wgc_capturer_win_unittest.cc" ]
       }
-      deps += [ ":desktop_capture_mock" ]
+      deps += [
+        ":desktop_capture_mock",
+        "../../system_wrappers:metrics",
+      ]
       public_configs = [ ":x11_config" ]
     }
   }

modules/desktop_capture/win/wgc_capture_source.cc

@@ -11,6 +11,8 @@
 #include "modules/desktop_capture/win/wgc_capture_source.h"
 
 #include <windows.graphics.capture.interop.h>
+#include <windows.h>
+
 #include <utility>
 
 #include "modules/desktop_capture/win/screen_capture_utils.h"
@@ -26,6 +28,18 @@ WgcCaptureSource::WgcCaptureSource(DesktopCapturer::SourceId source_id)
     : source_id_(source_id) {}
 WgcCaptureSource::~WgcCaptureSource() = default;
 
+bool WgcCaptureSource::IsCapturable() {
+  // If we can create a capture item, then we can capture it. Unfortunately,
+  // we can't cache this item because it may be created in a different COM
+  // apartment than where capture will eventually start from.
+  ComPtr<WGC::IGraphicsCaptureItem> item;
+  return SUCCEEDED(CreateCaptureItem(&item));
+}
+
+bool WgcCaptureSource::FocusOnSource() {
+  return false;
+}
+
 HRESULT WgcCaptureSource::GetCaptureItem(
     ComPtr<WGC::IGraphicsCaptureItem>* result) {
   HRESULT hr = S_OK;
@@ -36,14 +50,6 @@ HRESULT WgcCaptureSource::GetCaptureItem(
   return hr;
 }
 
-bool WgcCaptureSource::IsCapturable() {
-  // If we can create a capture item, then we can capture it. Unfortunately,
-  // we can't cache this item because it may be created in a different COM
-  // apartment than where capture will eventually start from.
-  ComPtr<WGC::IGraphicsCaptureItem> item;
-  return SUCCEEDED(CreateCaptureItem(&item));
-}
-
 WgcCaptureSourceFactory::~WgcCaptureSourceFactory() = default;
 
 WgcWindowSourceFactory::WgcWindowSourceFactory() = default;
@@ -73,6 +79,14 @@ bool WgcWindowSource::IsCapturable() {
   return WgcCaptureSource::IsCapturable();
 }
 
+bool WgcWindowSource::FocusOnSource() {
+  if (!IsWindowValidAndVisible(reinterpret_cast<HWND>(GetSourceId())))
+    return false;
+
+  return ::BringWindowToTop(reinterpret_cast<HWND>(GetSourceId())) &&
+         ::SetForegroundWindow(reinterpret_cast<HWND>(GetSourceId()));
+}
+
 HRESULT WgcWindowSource::CreateCaptureItem(
     ComPtr<WGC::IGraphicsCaptureItem>* result) {
   if (!ResolveCoreWinRTDelayload())

modules/desktop_capture/win/wgc_capture_source.h

@@ -31,6 +31,7 @@ class WgcCaptureSource {
   virtual ~WgcCaptureSource();
 
   virtual bool IsCapturable();
+  virtual bool FocusOnSource();
   HRESULT GetCaptureItem(
       Microsoft::WRL::ComPtr<
           ABI::Windows::Graphics::Capture::IGraphicsCaptureItem>* result);
@@ -93,6 +94,7 @@ class WgcWindowSource final : public WgcCaptureSource {
   ~WgcWindowSource() override;
 
   bool IsCapturable() override;
+  bool FocusOnSource() override;
 
  private:
   HRESULT CreateCaptureItem(

modules/desktop_capture/win/wgc_capturer_win.cc

@@ -77,6 +77,13 @@ bool WgcCapturerWin::SelectSource(DesktopCapturer::SourceId id) {
   return capture_source_->IsCapturable();
 }
 
+bool WgcCapturerWin::FocusOnSelectedSource() {
+  if (!capture_source_)
+    return false;
+
+  return capture_source_->FocusOnSource();
+}
+
 void WgcCapturerWin::Start(Callback* callback) {
   RTC_DCHECK(!callback_);
   RTC_DCHECK(callback);

modules/desktop_capture/win/wgc_capturer_win.h

@@ -94,6 +94,7 @@ class WgcCapturerWin : public DesktopCapturer {
   // DesktopCapturer interface.
   bool GetSourceList(SourceList* sources) override;
   bool SelectSource(SourceId id) override;
+  bool FocusOnSelectedSource() override;
   void Start(Callback* callback) override;
   void CaptureFrame() override;
 

modules/desktop_capture/win/wgc_capturer_win_unittest.cc

@@ -335,10 +335,17 @@ INSTANTIATE_TEST_SUITE_P(SourceAgnostic,
                                            CaptureType::kScreenCapture));
 
 // Monitor specific tests.
+TEST_F(WgcCapturerWinTest, FocusOnMonitor) {
+  SetUpForScreenCapture();
+  EXPECT_TRUE(capturer_->SelectSource(0));
+
+  // You can't set focus on a monitor.
+  EXPECT_FALSE(capturer_->FocusOnSelectedSource());
+}
+
 TEST_F(WgcCapturerWinTest, CaptureAllMonitors) {
   SetUpForScreenCapture();
-  // 0 (or a NULL HMONITOR) leads to WGC capturing all displays.
-  EXPECT_TRUE(capturer_->SelectSource(0));
+  EXPECT_TRUE(capturer_->SelectSource(kFullDesktopScreenId));
 
   capturer_->Start(this);
   DoCapture();
@@ -347,6 +354,22 @@ TEST_F(WgcCapturerWinTest, CaptureAllMonitors) {
 }
 
 // Window specific tests.
+TEST_F(WgcCapturerWinTest, FocusOnWindow) {
+  capturer_ = WgcCapturerWin::CreateRawWindowCapturer(
+      DesktopCaptureOptions::CreateDefault());
+  window_info_ = CreateTestWindow(kWindowTitle);
+  source_id_ = GetScreenIdFromSourceList();
+
+  EXPECT_TRUE(capturer_->SelectSource(source_id_));
+  EXPECT_TRUE(capturer_->FocusOnSelectedSource());
+
+  HWND hwnd = reinterpret_cast<HWND>(source_id_);
+  EXPECT_EQ(hwnd, ::GetActiveWindow());
+  EXPECT_EQ(hwnd, ::GetForegroundWindow());
+  EXPECT_EQ(hwnd, ::GetFocus());
+  DestroyTestWindow(window_info_);
+}
+
 TEST_F(WgcCapturerWinTest, SelectMinimizedWindow) {
   SetUpForWindowCapture();
   MinimizeTestWindow(reinterpret_cast<HWND>(source_id_));